1. Field of Invention
The present invention relates to a system for managing multiple radio modems integrated within a wireless communication device, and more specifically, to a multiradio control system enabled to create an operational schedule for a plurality of radio modems, wherein a radio modem having local control may manage unscheduled communication in view of various inputs.
2. Description of Prior Art
Modern society has quickly adopted, and become reliant upon, handheld devices for wireless communication. For example, cellular telephones continue to proliferate in the global marketplace due to technological improvements in both the quality of the communication and the functionality of the devices. These wireless communication devices (WCDs) have become commonplace for both personal and business use, allowing users to transmit and receive voice, text and graphical data from a multitude of geographic locations. The communication networks utilized by these devices span different frequencies and cover different transmission distances, each having strengths desirable for various applications.
Cellular networks facilitate WCD communication over large geographic areas. These network technologies have commonly been divided by generations, starting in the late 1970s to early 1980s with first generation (1G) analog cellular telephones that provided baseline voice communication, to modem digital cellular telephones. GSM is an example of a widely employed 2G digital cellular network communicating in the 900 MHZ/1.8 GHZ bands in Europe and at 850 MHz and 1.9 GHZ in the United States. This network provides voice communication and also supports the transmission of textual data via the Short Messaging Service (SMS). SMS allows a WCD to transmit and receive text messages of up to 160 characters, while providing data transfer to packet networks, ISDN and POTS users at 9.6 Kbps. The Multimedia Messaging Service (MMS), an enhanced messaging system allowing for the transmission of sound, graphics and video files in addition to simple text, has also become available in certain devices. Soon emerging technologies such as Digital Video Broadcasting for Handheld Devices (DVB-H) will make streaming digital video, and other similar content, available via direct transmission to a WCD. While long-range communication networks like GSM are a well-accepted means for transmitting and receiving data, due to cost, traffic and legislative concerns, these networks may not be appropriate for all data applications.
Short-range wireless networks provide communication solutions that avoid some of the problems seen in large cellular networks. Bluetooth™ is an example of a short-range wireless technology quickly gaining acceptance in the marketplace. A 1 Mbps Bluetooth™ radio may transmit and receives data at a rate of 720 Kbps within a range of 10 meters, and may transmit up to 100 meters with additional power boosting. Enhanced data rate (EDR) technology also available may enable maximum asymmetric data rates of 1448 Kbps for a 2 Mbps connection and 2178 Kbps for a 3 Mbps connection. A user does not actively instigate a Bluetooth™ network. Instead, a plurality of devices within operating range of each other may automatically form a network group called a “piconet”. Any device may promote itself to the master of the piconet, allowing it to control data exchanges with up to seven “active” slaves and 255 “parked” slaves. Active slaves exchange data based on the clock timing of the master. Parked slaves monitor a beacon signal in order to stay synchronized with the master. These devices continually switch between various active communication and power saving modes in order to transmit data to other piconet members. In addition to Bluetooth™ other popular short-range wireless networks include WLAN (of which “Wi-Fi” local access points communicating in accordance with the IEEE 802.11 standard, is an example), WUSB, UWB, ZigBee (802.15.4, 802.15.4a), and UHF RFID. All of these wireless mediums have features and advantages that make them appropriate for various applications.
More recently, manufacturers have also begun to incorporate various resources for providing enhanced functionality in WCDs (e.g., components and software for performing close-proximity wireless information exchanges). Sensors and/or scanners may be used to read visual or electronic information into a device. A transaction may involve a user holding their WCD in proximity to a target, aiming their WCD at an object (e.g., to take a picture) or sweeping the device over a printed tag or document. Near Field communication (NFC) technologies include machine-readable mediums such as radio frequency identification (RFID), Infra-red (IR) communication, optical character recognition (OCR) and various other types of visual, electronic and magnetic scanning are used to quickly input desired information into the WCD without the need for manual entry by a user.
Device manufacturers continue to incorporate as many of the previously discussed exemplary communication features as possible into wireless communication devices in an attempt to bring powerful, “do-all” devices to market. Devices incorporating long-range, short-range and NFC resources often include multiple mediums for each category. This may allow a WCD to flexibly adjust to its surroundings, for example, communicating both with a WLAN access point and a Bluetooth™ communication accessory, possibly at the same time.
Given the large array communication features that may be compiled into a single device, it is foreseeable that a user will need to employ a WCD to its full potential when replacing other productivity related devices. For example, a user may utilize a fully-functioned WCD to replace traditional tools such as individual phones, facsimile machines, computers, storage media, etc. which tend to be cumbersome to both integrate and transport. In at least one use scenario, a WCD may be communicating simultaneously over numerous different wireless mediums. A user may utilize multiple peripheral Bluetooth™ devices (e.g., a headset and a keyboard) while having a voice conversation over GSM and interacting with a WLAN access point in order to access the Internet. Problems may occur when these concurrent transactions cause interference with each other. Even if a communication medium does not have an identical operating frequency as another medium, a radio modem may cause extraneous interference to another medium. Further, it is possible for the combined effects of two or more simultaneously operating radios to create intermodulation effects to another bandwidth due to harmonic effects. These disturbances may cause errors resulting in the required retransmission of lost packets, and the overall degradation of performance for one or more communication mediums.
Evolving strategies for regulating air time between two or more radio modems contained in the same device often require a centralized (as a single component or distributed among various components) communication control enforcing an operational schedule for all active radio modems, the regulation of which helps to reduce the possibility of communication collisions between these active radio modems. However, in order for the operational schedule to be effective, the interplay of modem activity must be precisely controlled. This precision may be derived from the communication controller being synchronized with the modem by, for example, knowing the communication backlog and the timing patterns of the various active radio modems.
While centrally-controlled wireless resource management may be especially effective in optimizing some wireless mediums, other wireless mediums may continue to be problematic. For example, wireless protocols that are enabled for carrying synchronous data or may operate in a mode that uses fixed transmission and reception intervals, like GSM and Bluetooth™, may be more readily managed by a centralized controller because a schedule may be precisely defined without requiring large buffer time periods. However, other wireless mediums are not so predictive, such as WLAN. These unscheduled wireless mediums must compete for available transactional windows, and as a result, may require larger time periods to allow for determination of carrier availability. These determination periods, or contention periods, may require more time to complete a transaction, including both a message frame to be sent and also an acknowledgement frame to be received. If both of these frames are not sent/received in the time available, the message is considered unsuccessful, which may waste time in two ways: time is wasted in the initial failed WLAN message attempt (this time could have been successfully used by another wireless medium), and further, time is wasted in attempting to transmit the WLAN message again, which may still fail.
What is therefore needed is a system for managing wireless resources in the same device that utilize conflicting wireless communication mediums. The system should be enabled to manage both more predictable wireless communication mediums and wireless communication mediums that utilize unscheduled communication in order to avoid communication problems.